The present-day heating systems used in coke oven batteries in this country fall into two general classes: The gun-flue type and the underjet type. This invention relates more particularly to improvement in the apparatus for recirculating waste gases in a gun-flue type of coke oven battery.
The present invention is especially designed for high ovens in which the distribution of the heat of rich fuel gas to the tops of the flues is difficult when fuel gas of high calorific value is used. When coke oven gas that is given off by the carbonization of coal in the coke oven chambers, and that has a high calorific value, is used, it burns with a short, intense (hot) flame and it deposits free carbon both in the gun flues and in the high and low burners unless it is diluted.
Heretofore, in some instances, it has been the practice to provide ambient air from outside the battery for diluting and decarbonizing the gun flues and burners. In other instances it has been the practice to recirculate waste gases of combustion from within the battery, and more particularly, waste gases from the downflow vertical heating flues of the battery.
The effectiveness and the advantages of recirculating waste gas and mixing it with fuel gas in the burning walls of a coke oven battery has been well established and proven in underjet batteries. It has been established that such waste gas mixing with fuel gas provides improved vertical heat distribution in the burning flues.
However, in gun flue batteries the gas distribution header, or "gun flue", is located above the regenerator wall and just below the heating wall. This construction makes it nearly impossible to provide the desired jet aspirating action in the same manner as that provided in an underjet battery.
U.S. Pat. No. 3,192,134 describes and teaches the use of a recirculating duct at each end of the opposite ends of each pair of flues in each heating wall, at the level of the tops of the regenerators. Each recirculating duct connects the gun flue for one of the two sets of vertical combustion flues in each heating wall with the top of the regenerator that is communicably connected for the inflow of air and for the outflow of waste gas to the other set of combustion flues in the same heating wall.
The present invention is an improvement over the invention described in U.S. Pat. No. 3,192,134, as will become apparent to those skilled in the art from a reading of the following detailed description of a preferred embodiment of the present invention, shown in the drawings.